A variety of formulations for human use are stored a priori in the form of a dry particulate matter and are mixed with a liquid to form a liquid formulation shortly before use. This is the case, for example, with various nutritive formulas, including maternal milk substitute formulas, adult feeding formulas and a variety of drugs, e.g. antibiotics. The shelf life of such mixed liquid formulations is limited, and this dictates the need to prepare it into a liquid form only shortly before use. The limited shelf life of the liquid formulation is a result of a loss of activity of an active ingredient in the formula, accelerated oxidation once in solution, etc. When preparing a liquid formula from an a priori dry particulate formula, care should be taken to mix a correct amount of the two components, i.e. the dry particulate matter and the liquid, and in various applications it is also necessary to ensure that such mixing of component is performed under aseptic conditions, e.g. in the case of a drug, formulation to be administered parenterally.
Containers having separate compartments for storing two components, e.g. one being a dry particulate substance and the other being a liquid, both of which are mixed together prior to use, are known. Such two-compartment containers typically employ a breakable or displaceable partition between the two compartments. The partition is then either broken or displaced, as the case may be, to allow mixing.